MIG Welding Gas – The Fundamentals

By ced •  Updated: 07/07/21 •  6 min read

MIG welding is the most popular welding technique for metal joining due to its simplicity and low cost. It is a gas shielded process that utilizes only one electrode, the MIG (Metal Inert Gas) electrode which produces a gas-shielded arc which melts the workpiece.

The MIG welding process is also known as stick welding.

A typical MIG welder consists of an electrical generator, an electrode holder, a shielding gas supply system (generator or canister), and a torch with control and adjustment knobs. This torch usually has four settings: Low, Med, High and Forge (mixture of low and high).

The Electrode Holder holds the arc tip in place while protecting it from heat, moisture and dirt. The Shielding Gas Supply System contains the gas flow regulator, gas shutoff stem, hose assembly and pressure gauge.

In order to generate a MIG Welding arc, the MIG welding torch must be charged with shielding gas. To do this, you simply connect the torch to the gas supply system and turn on its power switch.

MIG welding electrodes come in a variety of shapes and sizes depending on their intended use. Generally, the electrode is connected to the MIG welding torch by way of a rod that is inserted into an electrode holder. This is commonly referred to as stick welding or stick-welding or stick-arc welding. MIG welding rods are also known as stick electrodes, stick tips, stick electrodes, stick wires or simply sticks.

The MIG electrode is made from a variety of materials, such as tungsten, molybdenum and cobalt-chrome. The electrode rods are available in diameters ranging from 0.20 – 0.50 inches. The size of the electrode depends on the size of the wire and the diameter of the workpiece being welded. The larger the workpiece being welded, and therefore requiring a larger diameter of welding rod, then the thicker and longer you should make your electrode rod to ensure proper heat transfer.

In comparison to gas tungsten arc welding (GTAW), MIG welding produces a lighter arc, which is ideal for use in ship construction or underwater applications. This reduced heat input can also help to prevent weld metal cracking.

The MIG welding process involves the movement of a shielding gas along a wire electrode to produce a weld across the workpiece. The gas moves along the wire electrode from its supply source through an aperture in the tip of the electrode, creating an arc between the electrode and the work piece. The arc is created by passing current (electrical current) through the gas shield wire and into the workpiece.

MIG welding typically requires less skill compared to GTAW, which makes it an excellent option for beginners and hobbyists alike. It is important to note that mixtures of gases are used to produce different welding characteristics, and that not all gases can be used with all types of electrodes.

MIG Welding Gas – The Basics

This gas is a mixture of tungsten and argon and will be used in the MIG welding process. It comes in a range of different units including but not limited to MIG wire, MIG gas, shielding gas or argon gas.

The majority of MIG welding gases are made up of a mixture of tungsten and argon.

The tungsten content determines how much heat is transferred from the handheld torch to the workpiece. The higher the percentage of tungsten, the more heat is transferred from the torch to the workpiece. The argon content affects how well the shielding gas protects the torch from dirt and moisture. This also gives you a choice of which type of electrode you wish to use for your MIG welding project.

Most commonly used types include Tenex (argon/tungsten/molybdenum), Tenex-Cobalt, Tenex-Molybdenum and Tenex-Molybdenum/copper.

MIG Welding Gas – Argon

Argon is a colourless, odourless gas with an extremely low boiling point (109.3 K) and high molecular weight which makes it ideal for welding applications. It is also less corrosive than most other gases and can be stored safely without the risk of damage to equipment or pipes.

Argon is a widely used shielding gas for MIG welding applications due to its low cost, purity and ease of handling. It is also very stable at room temperature and does not react with other metals.

MIG Welding Gas – CO2

CO2 is a colourless, odourless gas with a lower boiling point (94 K) and low molecular weight which makes it ideal for welding applications. It is also less corrosive than most other gases and can be stored safely without the risk of damage to equipment or pipes.

CO2 can be used in MIG welding applications with the use of MIG electrodes. It is a good choice for high-power welders due to its high energy density and high melting point. It also offers weld metal that is stronger compared to other gases that are more expensive, making it an excellent choice if you are welding thicker workpieces such as steel.

MIG Welding Gas – Tungsten

Tungsten is a dense metal with a high melting point (3,668 K) which makes it excellent at shielding gases. It is also highly resistant to corrosion and can be used in the MIG welding process. Tungsten is easily melted with an MIG electrode and can be used for high-power welders. However, it is not ideal for long-life applications due to its low heat transfer rate compared to other welding gases.

Which should you choose?

The best type of welding gas to use depends on your specific welding application.

For example, if you are welding steel pipes in a shipyard then an argon shielding gas will be less costly than a tungsten shielding gas. However, if you are welding carbon steel then the tungsten shielding gas will be more effective at reducing metal cracking.

If you are not 100% sure of which gas to use then it is best to consult an expert and they will be able to assist with making the correct choice that suits your needs. If you are still unsure about the gas type that will suit your needs, then it is best to contact an expert and they will be able to advise on the correct type for your application.

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